---
id: CVE-2025-39681
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init helper

  Since

    923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")

  resctrl_cpu…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init helper

  Since

    923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")

  resctrl_cpu…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.8, < 5.10.242'
  - 'linux_kernel >= 5.11, < 5.15.190'
  - 'linux_kernel >= 5.16, < 6.1.149'
  - 'linux_kernel >= 6.2, < 6.6.103'
  - 'linux_kernel >= 6.7, < 6.12.44'
  - 'linux_kernel >= 6.13, < 6.16.4'
  - linux_kernel = 6.17
  - debian_linux = 11.0
patched:
  - linux_kernel 6.16.4
published: '2025-09-05'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:17:58.477'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-39681'
references:
  - url: 'https://git.kernel.org/stable/c/62f12cde10118253348a7540e85606869bd69432'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7207923d8453ebfb35667c1736169f2dd796772e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/873f32201df8876bdb2563e3187e79149427cab4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a9e5924daa954c9f585c1ca00358afe71d6781c4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d23264c257a70dbe021b43b3bc2ee16134cd2c69'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d8df126349dad855cdfedd6bbf315bad2e901c2f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fb81222c1559f89bfe3aa1010f6d112531d55353'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-032379.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-457936.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00176
epssPercentile: 0.0704
ingestedAt: '2026-09-08T15:33:26.997Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init helper

Since

  923f3a2b48bd ("x86/resctrl: Query LLC monitoring properties once during boot")

resctrl_cpu_detect() has been moved from common CPU initialization code to
the vendor-specific BSP init helper, while Hygon didn't put that call in their
code.

This triggers a division by zero fault during early booting stage on our
machines with X86_FEATURE_CQM* supported, where get_rdt_mon_resources() tries
to calculate mon_l3_config with uninitialized boot_cpu_data.x86_cache_occ_scale.

Add the missing resctrl_cpu_detect() in the Hygon BSP init helper.

  [ bp: Massage commit message. ]

## Affected

- `linux_kernel >= 5.8, < 5.10.242`
- `linux_kernel >= 5.11, < 5.15.190`
- `linux_kernel >= 5.16, < 6.1.149`
- `linux_kernel >= 6.2, < 6.6.103`
- `linux_kernel >= 6.7, < 6.12.44`
- `linux_kernel >= 6.13, < 6.16.4`
- `linux_kernel = 6.17`
- `debian_linux = 11.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.16.4`